Grate bar



Nov. 20, 1923.

A. F. FR'ATTINGER GRATE BAR Filed Sept. 27 1920 Patented Nev 2 i923,

ARTHUR F. FRATTING-ER, O1 SEATTLE, WASHINGTON.

GRATE BAR.

Application filed September 27, 1820.

To all whom it may concern:

Be it known that I, ARTHUR FRATTIN- one, a citizen of the United Satates, residing at Zilcattle, in the county of King and State of Washington, have invented certain new and useful Improvements in Grate Bars, of which the following is a specification.

This invention relates to improvements in grate bars, and has for its principal objects the design and construction of a new and novel type of grate bar in which an in creased air passage .is provided at the point where the fuel rests upon the bar; to provide a bar in which all sharp and exposed corners and edges are eliminated, thus decreasing the tendency to overheating, and burning of the metal of the bar; to provide a bar construction in which heating, cooling and radiation will be approximately equal in all parts of the bar, thus eliminating tendencies to warp, check, etc., to provide a grate bar in which the cross-bars or mem bers are arched in such a way as to add greater stillness to the entire bar construc- "tion.

In grate bars in general, and particularly. in those used in burning such fuels as sawdust, it has been found very dillicult to secure a large enough air passage immediately adjacent the bed of fuel, and also to secure uniform distribution of the incoming air through the bed of fuel. This is particularly true in the case of sawdust fuel, for the reason that it is fine and packs quite tight. It is therefore desirable to utilize asimuch of the fuel bed as possible at the surface of the grate bar for distribution of air.

My bar is designed with this object in view and in such a way as to permit a practically uniform distribution and diffusion of air through the bed of fuel, and to provide means for maintaining a greater area of fuel exposed to the upward movement of air than is usual in grate bar construction.

The greatest deterioration of grate bars usually constructed is in the warping and breakage due to uneven heating and cooling, and to the burning of the metal of the bar. The former trouble is caused by improperly designed sections in the grate bar itself, while the latter trouble usually starts at exposed sharp corners and edges. In such sharp edges the heat acts on the metal from two directions at right angles to each other, and it will be readily under- Seriel No. 413,077.

stood that a sharp corner of the metal may be easily overheated and burned.

In my improved bar all such sharp corners and edges have been eliminated, thus preventing the abnormal tendency to burningthe bar. Once the sharp edges of a grate bar start to burn, the burning will continue on into the metal as the burned section becomes intensely hot and readily transmits this heat to th particles of unburned metal immediately adjacent to it. It will thus be seen that the elimination of exposed edges in grate bar construction is a highly important factor in the life of the grate bars.

Other objects will appear as my device is more fully explained in the following specification, illustrated in the accompanying drawing, and pointed out in the claims.

In the drawings, Figure 1 is a plan view of my improved grate bar. Fig. 2 is a side elevation of the same with parts broken away. Fig. 3 is a cross-sectional elevation talren near the center of the bar.

Referring more particularly to the drawings, numeral 1 indicates a pair of parallel side bars which are set vertically, and are provided with rounded upper edges 2 and similarly rounded lower edges 3. There is a slight taper to the bars 1.

Transverse or cross bars 4 are integrally connected to both of the longitudinal bars l. and are arched in such a way to extend above the top of the longitudinal bars 1. The cross oars l are also arched below as at 5, in order to eliminate excess metal, and to secure more even heating.

At the extreme ends of the grate bar, solid cross members (5 are provided and bearing lugs 7 extend downwardly from the members 6. It will be noted that the end cross members 6 extend slightly beyond the longitudinal bars 1, as at 8, in order to act as spacing lugs for adjacent grate bars. Similar spacing lug extensions 9 are provided centrally of the grate bar on the outside surface of longitudinal bars 1.

It will he noted that both the upper and lower edges of the cross bars 4: are rounded, and that the cross bars are slightly thicker at the top than at the bottom. The rounding at the top permits a greater surface of a bed of fuel 10 being exposed to the air as it passes up through the grate bar than is pos sible with a flat surface. It also provides a minimum of contact surface between the burning fuel and the grate bar, thus elimithe finely divided fuel which paclrs'on top of the grate bar, there is a distinct advantage in exposing a maximum of surface of the fuel beds to the incoming air as it passes through the grate bar, as otherwise the flow of air through tie fuel is much restricted. Enlargement of this air-receiving surface on the fuel bed permits ot the air passing upwardly through the bed of fuel at a much less velocity than is possible with the usual type of grate bars unless a very large grate area is provided. By maintaining a low velocity through the bed of fuel, the tendency to blow holes in the fuel bed is greatly eliminated.

The rounded lower edges of the cross bars 4 provide wide-mouthed orifices for the entrance of the air to the grate bar passages, thus eliminating eddies in the air current and increasing the carrying capacity of these passages.

The action of gases and liquids in passingrthrough orifices of ditlercnt shapes, and the distinct advantage in the gradual contraction oi the incoming side of the orifice and the gradual expansion at the opposite end, are too well understood to need further explanation here.

It will be understood that in a series of grate bars which combine a great number 0t openings. a relatively small increase in ellt eienc-v will result in a large saving in grate bar area and in grate. bar renewals.

While applicant is familiar with grate bars and grate bar construction, and is aware that there is a great variety of this product on the market today, as well as to the fact that the art is well worked, yet he is relying upon the improvements as set forth being of distinctly practical value over and above other grate bars now in use, and believes these improvements to be of a patentahle nature.

While applicant has shown an exact form and construction as illustrated, yet he does not wish to be limited to this exact form and construction except in so far as limited by the claims. 7

hat is claimed, is

1. In a grate bar, the combination of a pair of parallel longitudinal bars with rounded top and bottom edges, transverse bars intermediate the longitudinal bars and arranged in parallel relationship with each other, and with rounded edges at both top and bottom whereby flaring outlets for the air are provided at the tops of the bars and similar airinlets at the bottoms of the bars.

2. in a device of the class deserihed,the combination of a pair oi parallel longitudinal bars connected integrally at their ends, and provided with rounded top and bottom edges, arched cross bars arranged intermediately of said longitudinal bars in parallel relationship to each other and integral with the said longitudinal bar's, said cross bars having rounded top and bottom edges forming flarin air outlets at the top edges of the cross bars and"downwardly flaring air inlets at the bottom edges oi the cross bars.

3. In a device or the classdescribed the combination eta pair of parallel bars connected at their ends and in the same horiZon tal plane by end cross-members, all of said members and bars having rounded corners, arched cross-bars formed on radii of ditfer ent lengths, arranged progressively in a series transversely of and integrally of the" first mentioned bars, said cross-bars being arranged with those having the least radius 

